The present invention relates in general to surround sound encoding and decoding and more particularly concerns novel apparatus and techniques for encoding five major channels of a surround sound signal into two channels and decoding the encoded two channels to effectively retrieve the five major channels.
A typical surround sound signal includes at least left front, center front, right front, left rear and right rear signals. A typical prior art approach combines these signals into two signals that are typically decoded to recover a left front signal, a right front signal, a center front signal and a monophonic rear signal representative of the sum of the original left rear and right rear signals.
It is an important object of the invention to provide improved apparatus and techniques for encoding and decoding surround signals.
A feature of the invention resides in an adaptive matrix decode algorithm signal processor which allows for significantly improved steady-state adjacent channel separation, including a processor for generating true-stereo surround-sound signals with limited channel separation, and an additional center surround signal. This center surround signal can be decoded either from conventional matrix-encoded stereo signals or alternately furnished as an additional signal from discrete channel media.
Another feature resides in electroacoustically manipulating the front stage signals wherein the discretely panned left or right signal information can be xe2x80x9csqueezedxe2x80x9d inboard of the left and right channel loudspeakers. This feature facilitates reducing the perceived width of the front left/right sound stage image when listening to audio-for-video sound fields reproduced in concert with a video display device, thereby allowing conventional placement of the left/right channel loudspeakers spaced from the display device as in conventional stereophonic sound field reproduction without unnecessarily comprising the audio-for-video sound field reproduction.
Still another feature resides in means for encoding the original 5.1 channel source media into a conventional stereophonic signal, wherein the discrete left and right surround signals are monaurally encoded into a more conventional left total/right total signal format, herein referred to as LT, RT, but with much of the original directional concept preserved.